Ethylene gas is one of gases generated during ripening of vegetables and fruits, which reduces freshness. Apples, persimmons, mandarins, pears, and so on, among fruits, are known to generate a large amount of ethylene gas.
The ethylene gas is continuously generated during storage of the vegetables and fruits to excessively ripen and age the vegetables and fruits, degrading value of commodities of the vegetables and fruits.
For example, when fruits are stored in a sealed container, ethylene gas is continuously discharged. While there is no symptom on the exterior of the fruits for one to two weeks, the fruits are blackened after that.
In addition, when different kinds of fruits are stored together, the ethylene gas also wizens the different kinds of fruits. Accordingly, the fruits are recommended to be solely stored without sealing.
In order to solve the problem, the ethylene gas generated in the sealed space can be absorbed using an absorbent such as fibrous activated carbon or the like. However, since the method using the absorbent is restricted by an absorption capacity an the ethylene gas is discharged again when the capacity arrives at its limit, a periodic exchange of the absorbent is needed.
In addition, as the ethylene is decomposed and removed using an ultraviolet light mercury lamp and a structure coated with a photocatalyst, freshness of fruits and vegetables could be maintained. Korean Patent Application Laid-Open No. 10-2004-0064933, filed on Jul. 21, 2004, discloses a freshness maintaining apparatus for fruits, vegetables, and flowers, in which a photocatalyst is installed. However, an ultraviolet light mercury lamp is driven regardless of a height or weight of the stored fruits and vegetables or flowers, and thus, energy consumption becomes inefficient.